Video Technology

Also known as Moiré patterning. This is an effect that occurs when an analogue signal is sampled digitally at a sampling frequency less than twice the signal frequency. The effect can be minimised by a technique known as optical low-pass filtering.

The abbreviation BTU is used in the technical specifications for some electronic equipment. It stands for British Thermal Unit and describes (excerpt from Wikipedia) "... the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit ..." This describes the heat transfer of the device to its environment. This value is time-based and is thus specified in BTU/hr.

1 BTU is roughly equivalent to 1055 joules, or about 252 calories. 1 British pound is approximately 453.6 grams today. 1 °F is equal to roughly 0555 K.

With the interlacing procedure, the 25 (CCIR) complete TV (full frames) per second are generated from the corresponding half-frames (50 frames/second). In a full frame, the corresponding first half-frame is shown only in the odd lines (1, 3, 5, 7, ...) and the corresponding second half-frame is displayed in the even lines (2, 4, 6, 8, ...). Due to the inertia of the human eye, these two half-frames, drawn within one every 1/50th of a second, are perceived as a complete picture and seen as a sequence of full pictures with no flicker effect.

Progressive Scan, as opposed to interlaced video, scans the entire picture, line by line every sixteenth of a second. In other words, captured images are not split into separate fields as in interlaced scanning.

With QCIF, the resolution of CIF is reduced in similar proportion by half and the resolution becomes 176 x 144 pixels. The number of pixels is one-fourth that of CIF and this format supports moving images at a data rate of up to 30 frames per second.

The color temperature describes the (light) color that a source of light emits. However, the same color temperatures can be perceived differently depending on the individual. This is due to the respective number of "rods" and "cones" that are located on the retina of the human eye, which is responsible for the individual sense of perception.

°K refers to the Kelvin scale; 0 °K corresponds to -273,15 °C.

1,200 K looks yellow-orange, 6,500 K bluish white. The higher the color temperature, the more "harsher" the light tends to be perceived by human eyes.